A066473 - OEIS

A066473

Numbers having just seven anti-divisors.

38, 45, 52, 53, 58, 59, 63, 68, 73, 82, 83, 87, 88, 93, 97, 102, 103, 104, 108, 110, 116, 117, 126, 133, 135, 136, 138, 140, 142, 147, 153, 161, 163, 167, 170, 173, 176, 179, 192, 198, 199, 210, 229, 231, 232, 233, 234, 235, 243, 245, 252, 258, 259, 267, 269

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

See A066272 for definition of anti-divisor.

LINKS

Table of n, a(n) for n=1..55.

Jon Perry, The Anti-Divisor

Jon Perry, The Anti-divisor [Cached copy]

Jon Perry, The Anti-divisor: Even More Anti-Divisors [Cached copy]

MATHEMATICA

antid[n_] := Select[ Union[ Join[ Select[ Divisors[2n - 1], OddQ[ # ] && # != 1 & ], Select[ Divisors[2n + 1], OddQ[ # ] && # != 1 & ], 2n/Select[ Divisors[ 2*n], OddQ[ # ] && # != 1 &]]] }, # < n & ]]; Select[ Range[10^4], Length[ antid[ # ]] == 7 & ]

CROSSREFS

Cf. A066272.

Sequence in context: A072585 A050874 A144798 * A031409 A078550 A295491

Adjacent sequences: A066470 A066471 A066472 * A066474 A066475 A066476

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Jan 02 2002

STATUS

approved